Following the discovery of visible photoluminescence (PL) from porous silicon,1 Group IV semiconductor nanocrystals have become the focus of intense research due to their unique chemical and optical characteristics. The emergence of size dependent properties in nanoscale silicon and germanium has not only challenged semiconductor band structure models but also expanded the potential applications of these materials. Silicon and germanium nanocrystals (nc-Si, nc-Ge) both display size-dependent PL2,3 resulting from quantum confinement effects and have been investigated for potential integration into a variety of optoelectronic devices.4,5 
Germanium nanocrystals have been produced by ion implantation, laser ablation, anodization of bulk germanium, sputtering and solution based reduction.6-12 